Mixing and dispensing device

ABSTRACT

A mixing device for fluids, comprising a column within which there is an internal core, a space between the column and core defining a channel for the flow of the fluids, the surface of the column facing the core having fluid guide elements which impart helical flow in a first twist direction upon a fluid flowing along the channel, the surface of the core having fluid guide elements thereon which impart helical flow in an opposite twist direction upon the fluid. On part of the channel, the helical flow imparted to the fluid is predominantly in the twist direction of the elements on the core and on a part of the channel upstream or downstream of this part the helical flow imparted to the fluid is predominantly in the twist direction of the elements on the column.

FIELD OF THE INVENTION

This invention relates to a mixing device for mixing two or more fluidmaterials. The invention also relates to a dispensing device for two ormore fluid materials incorporating the mixing device so as to mix thefluid materials upon dispensing.

BACKGROUND OF THE INVENTION

Various mixing devices for fluid materials are known. One general typeof mixing device comprises a generally tubular column along which thetwo or more fluid materials are caused to flow together, the tubularcolumn having internal turbulence-creating elements which engage withand cause turbulence in the flow of fluid materials along the column.The turbulence causes the materials to mix thoroughly. One such mixingdevice is disclosed in U.S. Pat. No. 4,767,026, which comprises atubular column within which are a number of baffles in the form ofhelically twisted ribbons, the ribbons alternating in their direction ofhelical twist along the length of the column. The mixing device of U.S.Pat. No. 4,767,026 is disclosed in combination with a dispensing devicefor two fluid materials. Another such mixing device is disclosed in EP0212290 A which comprises a cylindrical passage tube provided with agroove on its inner peripheral wall and a shaft with a helical groove onits outer peripheral surface. The grooves on the shaft and the passagetube are of unchanging depth along the length of the tube.

Known mixing devices are inadequate for the thorough mixing of certainmaterials, e.g. medicinal or other healthcare formulations whichcomprise two or more fluid materials each of which contain substanceswhich are intended to interact on mixing to form a product.

It is an object of this invention to overcome this problem, in part atleast, and also to provide an alternative to known mixing devices. It isalso an object of the present invention to provide a mixing device whichis suitable for use with the type of small volume hand operateddispensing devices often used for healthcare products, such astoothpastes, gels etc. These generally comprise a number of reservoirsfor the respective substances each reservoir communicating with a handoperated pump which pumps the substance through a respectivecommunicating dispensing outlet. Such dispensing devices are well known,for example in U.S. Pat. Nos. 5,104,004 and 4,438,871 among many others.Other objects and advantages of the present invention will be apparentfrom the following description.

SUMMARY OF THE INVENTION

Accordingly, this invention provides a mixing device which is suitablefor mixing two or more fluid materials; comprising a generally tubularcolumn, within the column there being an internal longitudinally alignedcore, with a space between the column and the core defining a channelwhich is suitable for the flow of the fluid materials in an overalllongitudinal direction through the column, the channel having an inletend and an outlet end for the respective inlet and exit of fluidmaterial into and out of the channel, the inner surface of the columnwhich faces the core having one or more fluid guide elements thereonwhich impart helical flow in a first twist direction upon a fluidflowing longitudinally along the channel from the inlet end to theoutlet end, and the outer surface of the core which faces the columnhaving one or more fluid guide elements thereon which impart helicalflow in a second twist direction opposite to the first twist directionupon a fluid flowing longitudinally along the channel from the inlet endto the outlet end, characterised in that:

in part of the channel the helical flow imparted to the fluid ispredominantly in the twist direction of the guide elements on the coreand in a part of the channel upstream or downstream of this part thehelical flow imparted to the fluid flow is predominantly in the twistdirection of the guide elements on the column.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of non-limiting example onlywith reference to the following drawings:

FIG. 1 shows a longitudinal cross sectional view through the column of amixing device of this invention.

FIG. 2 shows a longitudinal cross sectional view through the core of amixing device of this invention.

FIG. 3 shows a longitudinal cross sectional view through a mixing deviceof this invention having the core of FIG. 2 in place of the column ofFIG. 1.

FIG. 4 shows a plan view of the column of FIG. 1 opened about a foldaxis.

FIG. 5 shows a longitudinal cross sectional view through the column ofanother mixing device of this invention.

FIG. 6 shows a side view of the core suitable for use with the column ofFIG. 5.

FIG. 7 shows a longitudinal sectional view through the core of FIG. 6.

FIG. 8 shows a longitudinal sectional view through a dispensing deviceincorporating the column and core of FIGS. 5, 6, and 7.

FIG. 9 shows detail of the outlet passages from reservoirs into themixing device of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment the tubular column is internally generallycircular-sectioned, and the core is preferably also externally generallycircular-sectioned, with the core coaxially aligned with the column. Theaxes of the said helical twists are suitably those of the column andcore.

Preferably toward the inlet end of the channel the helical flow impartedto the fluid is predominantly in the twist direction of the guideelements on the core, and downstream of the inlet end, i.e toward theoutlet end, the helical flow imparted to the fluid flow is predominantlyin the twist direction of the guide elements on the column.

The said fluid guide elements may be of various types, e.g. alignedelements, e.g. helically or part-helically aligned elements such as oneor more of baffles, vanes, ridges or grooves etc., or combinationsthereof upon the respective surfaces of the column and the core.

In a preferred embodiment, the said fluid guide elements comprise one ormore helical grooves in the surface of the column which faces the core,and one or more helical grooves in the surface of the core which facesthe column, the helical axes of the one or more grooves being generallylongitudinal, and the relative twist directions of the one or morehelical grooves on the column and core being opposite.

The said grooves may be present as cuts into the surfaces of the columnand/or core, or may be present between ridges raised from thesesurfaces.

In this preferred embodiment the one or more grooves on the column andthe core are in communication at their upper open faces and form aconvoluted channel between the inlet and the outlet of the channel. Theparts of the surface of the core and column, or the said ridges betweenthe grooves on respectively the core and the column, may be in contact.

The one or more grooves in the surface of the column and the core aresuitably continuous unbroken grooves. A single groove in the surface ofthe column and in the surface of the core may be used, or alternativelythere may be multiple grooves.

In this preferred embodiment the depth of the one or more grooves in thecolumn varies so as to be greater in the vicinity of the outlet end ofthe column than in the vicinity~ of the inlet end. Suitably the depth ofthe one or more grooves in the column may gradually increase from theinlet end toward the outlet end. In this embodiment the depth of the oneor more grooves in the surface of the core may vary so as to be greaterin the vicinity of the inlet end of the column than in the vicinity ofthe outlet end. Suitably the depth of the one or more grooves in thecore may gradually decrease from the inlet end toward the outlet end. Inthis preferred embodiment therefore, at the inlet end of the columndeeper grooves on the core face shallower grooves on the column, andtoward the outlet end of the column shallower grooves on the core facedeeper grooves on the column. This variation in the depth of the groovesin the core and column may occur gradually along the length of thecolumn, or alternately the variation in depth may be step-wise along thelength of the column.

In another preferred embodiment the internal cross section of the columndecreases, e.g gradually tapers or decreases step-wise from the inletend toward the outlet end, so that .internally the column is wider atthe inlet end than at the outlet end, and the external cross section ofthe core also decreases in a manner generally corresponding to thedecrease in internal cross section of the column. The column and coremay consequently be of a generally conical or frustro-conical shape,which may have a longitudinally straight, concave curved, convex curved,or stepped, sided shape.

Preferably, in a column which decreases in internal diameter with lengthas described above the depth of the one or more grooves may graduallyincrease in a way corresponding to the decrease in internal diameterwith length of the column, so that for example the bottom of the one ormore grooves lie at the same level, e.g. in a cylindrical surface.Preferably, in a tapering core as described above the depth of the oneor more grooves may gradually decrease in a way corresponding to thetaper of the core, such that for example the bottom of the one or moregrooves lie at the same level, e.g. in a cylindrical surface.

The profile, width and helical pitch of the said grooves may also differat different places on the column and core. A suitable profile, helicalpitch and dimensions for the above described helically aligned guideelements, e.g. the said grooves, for any particular application will beapparent to those skilled in the art or may be determined by simpleexperimentation. A suitable cone angle for the above-mentioned taperingcore and column is 1°-4° particularly 2°-4°.

Although in the above described preferred embodiment the variation indepth of the groove(s) on the core is such that the groove(s) is/aredeeper toward the inlet end of the core and the variation in depth ofthe groove(s) on the column is such that the groove(s) is/are deepertoward the outlet end of the column, the reverse embodiment is alsoincluded within the invention, i.e the variation in depth of thegroove(s) on the core being such that the groove(s) is/are deeper towardthe outlet end of the column and the variation in depth of the groove(s)on the column being such that the groove(s) is/are deeper toward theinlet end of the column.

At the inlet end of the column the two or more fluids may be fed intothe column in separate streams, which may for example be side-by-side,coaxial, or radially segmented streams. Alternatively the fluids may bepartly pre-mixed, for example by causing separate streams of the fluidsto flow into a pre-mixing region upstream of the column. Suitabledispensing devices with dispensing columns to achieve this are known inthe art. At the inlet and/or outlet end the column may be provided witha filter device or other device to modify the characteristics of thestream of mixed fluid.

The column and core may be made by simple injection moulding techniques,for example of moulded plastics materials such as polypropylene, nylonetc. The column and core of the mixing device of the invention may eachbe of integral construction or one or each may be made of two or morepart construction. For example the column may be made as a shell and aseparate core may be inserted therein, and retained in place by suitablemeans such as snap-fit etc. which will be apparent to those skilled inthe art. The mixing device of the invention may be made as a separatenozzle-like extension or adapter for attachment to the outlet passagesof a dispenser for two or more fluid materials of the kind discussedabove.

The invention also provides a dispensing device for two or more fluidmaterials incorporating the mixing device as described above to mix thefluid materials therein upon dispensing them.

Such a dispensing device may comprise two or more respective reservoirssuitable to contain the two or more fluid materials, each reservoirbeing provided with displacement means to transfer material from thereservoir through an outlet opening in each reservoir, into the inletend of the mixing device.

The dispensing device may comprise two or more separate storagereservoirs each reservoir containing respective fluid material; eachreservoir being in the form of a cylinder, each reservoir having arespective outlet passage and a piston moveable internally along thecylinder to force the material out through the outlet passage of thereservoir, and a mixing device as described above in downstreamcommunication with the outlet passage of each reservoir and from whichthe product is dispensed.

The dispensing device may alternatively comprise two or more collapsiblereservoirs, e.g. plastics material or metal foil or laminate tubes, eachreservoir containing respective fluid material, each reservoir having arespective outlet passage which is respectively in downstreamcommunication a mixing device as described above in downstreamcommunication with the outlet passages and from which the product isdispensed.

The dispensing device may alternatively comprise two or more separatestorage reservoirs containing the respective two or more fluidmaterials; two or more hand-operable pumps respectively in communicationwith said two or more separate storage reservoirs and capable of pumpingthe fluid material therein from the reservoirs and alone two or morerespective separate outlet passages which are respectively in downstreamcommunication with the pumps, and a mixing device as described above indownstream communication with the outlet passages and from which theproduct is dispensed.

The dispensing device of the invention may be made of plasticsmaterials. The dispensing device may be provided with appropriateclosures to prevent leakage or contamination, and these may be tamperevident. The dispensing device may be provided with appropriate lockingmechanisms to prevent premature operation of pistons or pumps etc.

The mixing device of the invention provides an improved mixing effect byvirtue of the fact that considerable turbulence and shear is caused inthe stream of fluids flowing through the channel by the simultaneousimparting of opposite helically twisted flow to the fluids. This isachieved in a more simple manner in the mixing device of the inventionthan in the device of for example U.S. Pat. No. 4,767,026, in that onlyone core element need be used instead of the several “ribbons” of U.S.Pat. No. 4,767,026. Also improved mixing is achieved over the mixingdevice of EP 0212290 A because of the shear and turbulence causedbecause in part of the channel the helical flow imparted to the fluid ispredominantly in the twist direction of the guide elements on the columnand at a part of the channel upstream or downstream of this part thehelical flow imparted to the fluid flow is predominantly in the twistdirection of the guide elements on the core.

Referring to FIGS. 1, 2, 3 and 4, a mixing device which is suitable formixing two or more fluid materials comprises a generally tubular column(1). Within the column (1) as shown in FIG. 3 there is an internal core(2) longitudinally aligned with the tube axis of the column 1. In FIG. 2the core (2) is shown independently of the column (1). The tubularcolumn (1) is internally generally circular-sectioned, and the core (2)is also externally generally circular-sectioned, and when in place asshown in FIG. 3 the core (2) is coaxially aligned with the column (1).

In the internal surface of the column (1), which faces the core (2) whenthis is in place as shown in FIG. 3, is a continuous unbroken helicalgroove (3), running from the inlet end (4) of the column (1) to theoutlet end (5) of the column (1). In the surface of the core (2), whichwhen the core (2) is in place in the column (1) as shown in FIG. 3 facesthe column (1), is a continuous unbroken helical groove (6) running fromthe inlet end (4) of the core (2) to the outlet end (5) of the core (2).The helical axes of the grooves (3), (6) is generally longitudinal,aligned with the tube axis of the column (1), and the relative twistdirections of the helical grooves (3), (6) respectively on the column(1) and core (2) are opposite.

When the core (2) is in place within column (1) as shown in FIG. 3, thegrooves (3), (6) are in communication at their upper open faces, andform a space between the column (1) and the core (2) which defines achannel (7) which is suitable for the flow of fluid materials (notshown) in a longitudinal direction, as shown by the arrow in FIGS. 1 and3, through the column (1). The channel (7) has an inlet end at the inletend (4) of the column (1), and an outlet end at the outlet end (5) ofthe column (1) for the respective inlet and exit of fluid material intoand out of the channel (7).

The helical groove (3) imparts helical flow in a first twist direction(i.e. clockwise) upon the fluid flowing longitudinally along the channel(7) from the inlet end (4) to the outlet end (5), and the groove (6)imparts helical flow in a second twist direction opposite to the firsttwist direction (i.e. anticlockwise) upon a fluid flowing longitudinallyalong the channel (7) from the inlet end (4) to the outlet end (5).

The internal cross section of the column (1) tapers from the inlet end(4) toward the outlet end (5), so that internally the column (1) iswider at the inlet end (4) than at the outlet end (5). The externalcross section of the core (2) also tapers in a manner generallycorresponding to the internal taper of the column (1). The taperingcolumn (1) and core (2) are consequently of a generally frustro-conicalshape, with straight sides, and with a cone angle for the taper of2°-4°.

The depth of the groove (3) in the column (1) is greater in the vicinityof the outlet end (5) of the column (1) than in the vicinity of theinlet end (4). The depth of the groove (3), as measured radially fromthe upper open face toward the outer surface of the column (1) graduallyincreases from the inlet end (4) toward the outlet end (5). As thecolumn (1) is internally tapering, the depth of the groove (3) graduallyincrease in a way corresponding to the taper of the column (1), suchthat the bottom of the groove (3) lies at the same level throughout itslength, lying in a cylindrical surface.

Similarly, the depth of the groove (6) in the surface of the core (2),as measured radially, is greater in the vicinity of the inlet end (4)than in the vicinity of the outlet end (5), the depth graduallydecreasing from the inlet end (4) toward the outlet end (5). As the core(2) is externally tapering the depth of the groove (6) graduallydecreases in a way corresponding to the taper of the core (2), so thatthe bottom of the groove lies at the same level throughout its length,lying in a cylindrical surface.

The mixing device of the invention as illustrated in FIGS. 1 to 4 is ofmulti-part construction. The column (1) is made as a shell, which asshown in FIG. 4 is in two halves (1A, 1B) joined by a film hinge (8)which when closed to form the column are held together by clips (9). Aseparate core (2) is inserted into the column (1), and is retained inplace by integral fins (10), within a collar (11) at the inlet end,there being apertures between the fins (10) for the fluid. At the outletend the core (2) is retained within the column (1) by a plug (12), againwith apertures (not shown) for the fluids.

The mixing device is made as a nozzle-like adapter which may beconnected to the outlet channel (13) of a dispenser for two or morefluid materials of the kind discussed above.

At the inlet end (4) of the column (1) two or more fluids may be fedinto the column in separate or partly pre-mixed streams, and theconsiderable turbulence and shear caused in the stream of fluids by thesimultaneous imparting of opposite helically twisted flow to the fluidsas they flow through the channel (7) causes them to be thoroughly mixedby the time they reach the outlet end (5).

The entire mixing device illustrated in FIGS. 1 to 4 may be made ofplastics materials by standard techniques of injection moulding.

Referring to FIGS. 5-8 the overall arrangement is similar to that ofFIGS. 1 to 4, and corresponding parts are numbered correspondingly. Inthe description below, only differences between the parts shown in FIGS.5-8 and those shown in FIGS. 1-4 are described in detail.

The column (1) is made, in one-part construction, by injection mouldingof plastics materials. Near its inlet end (4) the internal surface ofthe column (1) is provided with grooves (14) which enable a snap-fitconnection to corresponding ridges on the neck part (15) of a reservoirunit (16) comprising a pair of side-by-side reservoirs (16A, 16B). Atits outlet end (5) the column (1) is provided with a tear-off tamperevident closure disc (17), with a pull ring (18). The disc (17) islinked to the outlet end (5) by only an integral tearable thin filmlink.

The core (2) is hollow, and has an internal socket (19) allowingengagement with a retaining fin (20) on the reservoir unit (16). At itsoutlet end the core (1) is provided with a centering flange (21) whichfits into the outlet end of the column (1). The flange (21) is piercedby a number of holes (one shown, 22) to allow passage of fluid materialthrough.

The reservoir unit (16) comprises a pair of side-by-side reservoirs(16A, 16B) linked in an integral construction. The neck part (15)includes outlet passages (23A, 23B) which when the mixing device is inplace allow fluid material to flow from each reservoir (16A, 16B) intothe inlet end of the channel (7). As shown in FIG. 9, being a view inthe direction of the arrows in FIG. 8, each outlet passage (23A, 23B) ispart circular, centred about the axis of the column (1).

The reservoir unit (16) is provided with a piston unit (24) comprisingtwo integrally linked pistons (24A, 24B), respectively one in eachreservoir (16A, 16B). The piston unit (24) may be pushed in thedirection of the arrow by button (25). The internal surfaces of thereservoirs (16A, 16B) are provided with abutment surfaces (not shown) toprevent inadvertent removal of the pistons (16A, 16B). The piston unit(24) includes a tear-off member (26) which prior to use abuts againstthe reservoir unit (16) to prevent premature operation of the pistonunit (24).

In use, the closure disc (17) and member (26) are torn off, and thepiston unit (24) may be pushed by hand action applied to button (25) inthe direction of the arrows to force fluid material in the reservoirs(16A, 16B) along the channel (7). Convenient finger rests (27) areprovided to enable the dispensing device to be used in the manner of asyringe.

What is claimed is:
 1. A mixing device which is suitable for mixing two or more fluid materials; comprising a generally tubular column (1), within the column (1) there being an internal longitudinally aligned core (2), with a space between the column (1) and the core (2) defining a channel (7) which is suitable for the flow of the fluid materials in an overall longitudinal direction through the column (1), the channel (7) having an inlet end (4) and an outlet end (5) for the respective inlet and exit of fluid material into and out of the channel (7), the column (1) having an inner surface which faces the core (2), said inner surface having one or more helical grooves thereon having a first twist direction and the core having an outer surface which faces the column (1), said outer surface also having one or more helical grooves thereon having a second twist direction opposite to the first twist direction, the said grooves comprising the channel wherein the depth of the one or more grooves (3) in the column (1) is greater in the vicinity of the outlet end (5) of the column (1) than in the vicinity of the inlet end (4).
 2. A mixing device according to claim 1 wherein the tubular column (1) is internally generally circular-sectioned, and the core (2) is also externally generally circular-sectioned, with the core (2) coaxially aligned with the tube axis of the column (1).
 3. A mixing device according to claim 1 wherein the internal cross section of the column (1) decreases from the inlet end (4) toward the outlet end (5), so that internally the column (1) is wider at the inlet end (4) than at the outlet end (5), and the external cross section of the core (2) decreases in a manner generally corresponding to the internal decrease in internal cross section of the column.
 4. A mixing device according to claim 3 wherein the column (1) and core (2) are of a generally frustro-conical shape, with a cone angle for the taper of 1°-4°.
 5. A dispensing device for two or more fluid materials comprising two or more separate storage reservoirs each reservoir having a respective outlet passage, each reservoir containing respective fluid material, each reservoir being provided with displacement means to force the material out through the outlet passage of the reservoir, and a mixing device as claimed in claim 1 being in downstream communication with the outlet passage of each reservoir such that material displaced from the reservoirs enters the mixing device at the inlet end thereof, and from the outlet end of the mixing device the product being the mixed two or more fluid materials may be dispensed.
 6. A mixing device which is suitable for mixing two or more fluid materials; comprising a generally tubular column (1), within the column (1) there being an internal longitudinally aligned core (2), with a space between the column (1) and the core (2) defining a channel (7) which is suitable for the flow of the fluid materials in an overall longitudinal direction through the column (1), the channel (7) having an inlet end (4) and an outlet end (5) for the respective inlet and exit of fluid material into and out of the channel (7), the column (1) having an inner surface which faces the core (2), said inner surface having one or more helical grooves thereon having a first twist direction and the core having an outer surface which faces the column (1), said outer surface also having one or more helical grooves thereon having a second twist direction opposite to the first twist direction, the said grooves comprising the channel wherein the depth of the one or more grooves (6) in the surface of the core (2) is greater in the vicinity of the inlet end (4) of the column (1) than in the vicinity of the outlet end (5).
 7. A mixing device according to claim 6 wherein the tubular column (1) is internally generally circular-sectioned, and the core (2) is also externally generally circular-sectioned, with the core (2) coaxially aligned with the tube axis of the column (1).
 8. A mixing device according to claim 6 wherein the internal cross section of the column (1) decreases from the inlet end (4) toward the outlet end (5), so that internally the column (1) is wider at the inlet end (4) than at the outlet end (5), and the external cross section of the core (2) decreases in a manner generally corresponding to the internal decrease in internal cross section of the column.
 9. A dispensing device for two or more fluid materials comprising tow or more separate storage reservoirs each reservoir having a respective outlet passage, each reservoir containing respective fluid material, each reservoir being provided with displacement means to force the material out through the outlet passage of the reservoir, and a mixing device as claimed in claim 6 being in a downstream communication with the outlet passage of each reservoir such that material displaced from the reservoirs enters the mixing device at the inlet end thereof, and from the outlet end of the mixing device the product being mixed two or more fluids may be dispensed. 